Its a good point, no one will really know how the split really affected economic and social growth but its nice to speculate on occasions.
I think the best case study that can be made on what the affects of country integration are on social and economic frameworks is the process of integration of the Two Germanys in the 1980's--1990's.
They are definitely on a smaller scale then what a South and North Korea Integration would be, but even on that small scale it took several years to really recoup the issues, both socially and economically, that the integration caused. This is not including the few years leading up to the symbolic fall of the Berlin Wall, that was used to prepare the countries for integration.
IF and its a big IF...
The two Koreas were to come together again, we are talking about something this is in scale about 3 to 4 times bigger then the Germany combination. Also we would lack the Pre planning stage. This is because i really think there is only 2 conclusions to the North. They keep staying a 3rd world country until hell freezes over OR due to a whole variety of issues they just implode from within, taking the country's social and economic framework with it.
So whatever really happens its really not going to be pretty and any conclusion is going to put increasing strain on South Korean Stability and Growth rates.
If the North really does implode on itself, It really does become a every man for themselves scenario, which is going to be MAJOR humanitarian crisis. There is no policy or funds in any charity or country that could adequately provide integration and assistance in the case that North Korea Fails completely, Definitely the South doesn't have the funds or the policies to deal with a mass influx of North Korean, its unfortunately wishful thinking to believe they do at this point. We are talking about 23 million people (according to Google) that are going to be suddenly displaced, with no government or protection. Most of these people grew up knowing nothing but the North Korean way of life, and the sudden cultural shock of losing their "Great Leader" and country could cause them to act erratically, and a country with the worlds largest standing army is not something you want to act erratically in a region that's populated by the South, Japan and China.
Then there is obviously what would happen if the North just gives up and launches a pre-emptive strike on the region. There is a great article writen by someone in American Department of Defense in 2003 here
http://www.globalsecurity.org/org/ne...rean-war01.htm
Pretty much it outlines what a modern war on the Korean Peninsula is going to look like.
It's also relatively simple, The North Won't survive for more than a few days under the the combined attack of an American led UN force. Bigger issue here is the massive economic and citizen death that is going to occur if such an event occurs. The North has the capability to bombard Seould with artillery strike and level the city in less than a day. Its a MINIMUM 1 million, worse here is the estimate from the site "One estimate, cited by GlobalSecurity.org, says North Korea could kill 38 percent of Seoul's 12 million people by hitting the city with 50 missiles carrying nerve gas."
That's over 4 million people in less then a few hours.
This is not to mention their attacks on Japan and China would be like.
There is a good reason that America hasn't eliminated North Korean yet, like Iraq. A Normal Barking dog isn't very scary. A barking Dog, Frothing at the mouth, with a history of craziness and a nuke under its leg is a completely different story....
And during all this chaos, the Chinese will just expand their borders to cover more of the Korean Peninsula, Considering our efforts trying to Maintain Dokdo or the East Sea, i don't think we will provide too much resistance to any land grab by the Chinese -.-"